Friday 24 August 2012 13.11 EDT
First published on Friday 24 August 2012 13.11 EDT

On the surface at least, the killer and his victims agreed on one thing. Anders Behring Breivik and the families of many of the dead welcomed the court verdict that he was sane enough to bear responsibility for mass murder, putting him in jail most probably for life.

But their satisfaction sprung from very different sources. For the bereaved relatives and the 242 wounded survivors of Breivik's killing spree, the 21-year sentence with the prospect of further indefinite detention offered at least the grim consolation that he had not escaped accountability.

The 33-year-old defendant, meanwhile, had fought hard to be accepted as sane because in his eyes such a finding buttressed his xenophobic creed. He anticipates his jail cell as a platform from which to capitalise on his notoriety and broadcast those beliefs.

He will have a computer with no internet connection, and is expected to use it to write books as well as updates to the extremist manifesto demonising multiculturalism that he sent out by email on the day of the attacks, 22 July last year. His right to disseminate such work from prison is likely to be the subject of further legal dispute.

"He might write up something and he might be able to get it published. There is freedom of the press," said Tor Bach, the head of Vepsen, an Oslo-based organisation that monitors extreme right. "But so what? The number of potential followers will still be very low."

Tore Bjorgo, a professor at the Norwegian Institute of International Affairs, said Breivik had received a lot of correspondence. "It's not impossible he will get a following. The question is how much space will he get from the prison regime. The problem is we have not had anyone like this before and I'm not sure that the present regulations can handle him. They will have to be as strict as possible but it is also important not to make a Breivik an exception. We don't want to set up a Guantánamo for Breivik."

Breivik's notoriety has not escaped the attention of other extremists on an economically traumatised continent. Last week Czech police arrested a 29-year-old man in Ostrava who was found with weapons, explosives and police uniforms in his flat and who used the name Breivik online.

Anthony Painter, a co-director of the Extremis Project, which tracks far-right activity from London, said: "[Breivik] got the martyrdom he craved, and there is always the risk of copycats. The motivating forces are there for an individual wanting to be as high-profile as Breivik."

However, he said: "Such actions take an inordinate amount of planning, knowledge and expertise, and you would think security services are now more acutely aware of the risk."

Andrea Mammone, a historian at Royal Holloway college and an expert on the European far right, said the Breivik verdict had come at a time when extremist pan-national networks were growing amid recession, austerity and alienation in Europe and the US.

"The more structured parties will want to avoid any reference to Breivik because electorally it will be costly, but his views are widely shared," Mammone said. "The extreme rightwing is generally growing and there is an underground attempt to build super-national organisations, challenging Islam, challenging elites and trying to play the card of the economic crisis."

There have been gatherings of such international networks in Rome and Hungary this year, and one is planned in York this month. Mammone said Breivik's name had not yet proved a rallying point for such gatherings, and it was too soon to predict whether it would become so in the wake of the verdict.